Field of the Invention
Embodiments generally relate to input sensing and, in particular, to input sensing by driving sensor electrodes for absolute capacitive sensing.
Description of the Related Art
Input devices including proximity sensor devices (also commonly called touchpads or touch sensor devices) are widely used in a variety of electronic systems. A proximity sensor device typically includes a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location, and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems (such as touchpads integrated in, or peripheral to, notebook or desktop computers). Proximity sensor devices are also often used in smaller computing systems (such as touch screens integrated in cellular phones or tablet computers).
Input devices may employ transcapacitance (or “mutual capacitance”) to determine a change in capacitive coupling relating to the presence of an input object in a sensing region. Given an array of sensing regions, transcapacitance sensing can be used to generate a capacitive image, from which multiple input objects can be resolved at a given time (e.g., “multi-touch” sensing). However, transcapacitance can produce less reliable results as the distance between the input objects and the sensing regions increases (e.g,. proximity or hover sensing).